• A mixture of presentations and exercises
• Program and course materials are located at https://mmollerup.github.io/RVietnam/
• Exercises with hints and solutions
  • Use hints
• Ask

• R is a programming language for statistical programming and graphics
• Opensource, powered by the R Foundation for Statistical Computing
• Driven by a volunteer community that develops packages for every imaginable purpose

• A collection of data management, modeling, and visualization packages that “share underlying design philosophy, grammar, and data structures”
• Characterized by the use of so-called “pipes”, where the output of each line’s code is passed on to the next link in the pipe. This generally makes for more readable code.
• Load with library(tidyverse)

• Integrated Development Environment (IDE)
• Aggregates all convenient information and procedures into one single place
• Allows you to work in projects
• Manages your code with highlighting
• Gives extra functionality (reports in html, doc, pfd, webpages…)
• Allows for integration with version control routines, such as Git.

This is why we use R-Studio.

• A feature of RStudio.
• Basically: A project is a folder that contains a .Rproj file. When you open the project file, you start a new session, with your working directory in the project folder
  • working directory: Where R looks for files you want to load and puts files you want to save.
    • You can see your working directory with getwd(), and you can set it with setwd() - but you should not do it, because it results in more fragile code.
• It is good practice to keep all files belonging to a project in the same place.
• Projects make it easier to separate separate analyses, and make code more portable and robust.

• Create a separate folder and an RStudio project file for each project.
• Put your code files there.
• Save output there.
• Save output with code not as point-and-click.
• When you code paths to files, do so relative to your project folder.

## Good!:
saveRDS( MyObject, "/Output/MyObject.RDS")

## No!:
saveRDS( MitObject, "C:/Documents/This Project/Output/MyObject.RDS")

(Also note: R uses / and not \ in paths to files)

• Everything that is published on the Comprehensive R Archive Network (CRAN) and is aimed at R users, must be accompanied by a help file.

• If you know the name of the function that performs an operation, e.g. anova(), then you just type ?anova or help(anova) in the console.

• If you do not know the name of the function: type ?? followed by your search criterion. For example ??anova returns a list of all help pages that contain the word ‘anova’

• Alternatively, the internet will tell you almost everything you’d like to know (and then some)

• Sites such as http://www.stackoverflow.com and http://www.stackexchange.com, as well as Google can be of tremendous help.

  • If you google R related issues; use ‘R:’ as a prefix in your search term

• R works with objects that consist of elements. The smallest elements are numbers and characters.

  • These elements are assigned to objects.
  • A set of objects can be used to perform calculations
  • Calculations can be presented as functions
  • Functions are used to perform calculations and return new objects, containing calculated (or estimated) elements.
  • View the objects you have created in the Environment tab on the right of RStudio

Assigning things in R is very straightforward:

• you just use <-

For example, if you assign the value 100 (an element) to object a, you would type

a <- 100

Calling things in R is also very straightforward:

• you just use type the name you have given to the object

For example, we assigned the value 100 to object a. To call object a, we would type

a

## [1] 100